The present invention relates to a method of teaching a robot with a travelling axis off-line.
A so-called off-line teaching met hod has been publicly known, in which a numerical model that expresses the dimensions and pro files of a robot and its peripheral apparatuses is constructed in a computer, an image based on the above-described model of the above-described robot and peripheral apparatuses is displayed on the display of the above-described computer, and a operation program of the above-described robot is prepared in the above-described computer.
Many of today""s robots have six degrees of freedom (three degrees of movement and three degrees of rotation), and can cause an end effecter attached to the tip end thereof to take an arbitrary posture at an arbitrary position. In order to widen the operation range of such robots, there are cases where a robot is mounted on a travelling carriage that runs on a linear travelling track and can stop at an arbitrary position. Since the travelling carriage is controlled by a controller apparatus of the robot together with the other axes, such a robot is generally called a xe2x80x9crobot with a travelling axisxe2x80x9d.
However, since a prior art robot with a travelling axis has a degree of freedom in the travelling axis in addition to three degrees of freedom and has four degrees of freedom in total, there is a problem in that the degree of freedom is redundant. That is, since there are infinite combinations of the movement quantities of the four degrees of freedom when positioning the tip end of the robot with a travelling axis at an appointed position, the movement quantities of the above-described four degrees of freedom cannot be monistically determined.
In the prior art, when preparing an operation program for a robot with a travelling axis by off-line teaching, such a procedure is repeated, in which an operator inputs the quantity of movement of the travelling axis and moves the robot, and makes sure, through simulation, of whether or not the robot can take an appointed posture at the moved position. That is, the operator confirmed the quantities of movement of the travelling axis by trial and error. Therefore, there was another problem in that the teaching consumes much time. There was still another problem in that the time required for the teaching becomes uneven, depending on the experience and skill of an operator.
Therefore, it is an object of the invention to provide a method of teaching a robot with a travelling axis off-line, by which the movement quantity of the travelling axis of the robot with a travelling axis can be monistically determined. In order to solve the above-described object, the invention is such that the robot with a travelling axis determines the position of the above-described travelling axis of the above-described robot with a travelling axis, at which the distance between the coordinate origin of the above-described robot with a travelling axis and a movement target point is minimized, to be the final teaching position when a control point of the above-described robot with a travelling axis agrees with the above-described movement target point, which departs from an arbitrary initial position and initial posture. Also, a component of a vector, which is oriented from the above-described control point toward the above-described movement target point, parallel to the above-described travelling axis is obtained when the above-described robot with a travelling axis takes the above-described posture at the above-described initial position, and the position at which the robot has moved by the above-described component of the above-described vector, is determined to be the above-described final teaching position. In addition, a position on the above-described travelling axis, at which the above-described movement target point exceeds the outer edge of an operation range of the control point of the above-described robot with a travelling axis and enters the above-described operation range when the above-described robot with a travelling axis approaches the above-described movement target point from the above-described initial position on the above-described travelling axis, is taken as the first position, and a position on the above-described travelling axis of the above-described robot with a travelling axis, where the distance between the coordinate origin of the above-described robot with a travelling axis and the above-described movement target point is minimized, is taken as the second position, wherein an arbitrary point between the above-described first position and the above-described second position is determined to be the final teaching posit ion of the above-described robot with a travelling axis on the above-described travelling axis. Further, where the above-described movement target point resides outside the operation range of the above-described control point when the above-described robot with a travelling axis is located at the above-described final position, the above-described robot with a travelling axis is repeatedly moved at an appointed pitch from the above-described final position to the above-described initial position until the above-described movement target point enters the operation range of the above-described control point.